Meat emulsifying and processing system

ABSTRACT

A meat emulsification system for producing meat products with optimum emulsification stability. The emulsification system includes a perforated plate and a rotary multibladed cutter disposed adjacent an upstream side thereof which is operable for breaking the meat into a fine emulsion and raising the temperature thereof as it is directed through the perforated plate. Meat to be emulsified is fed to the emulsifying mill by a positive displacement pump which creates a positive pressure at the inlet of the mill and which can be varied in order to control the through put of the mill, and thus, the temperature rise of the product discharged from the mill for achieving optimum emulsification stability in the processed product. The emulsification system permits the use of a perforated plate with smaller sized apertures and a rotary cutter with greater numbers of blade carrying arms than heretofore possible for producing a finer and more cohesive emulsion, while yet permitting relatively precise control of the temperature rise during emulsification. The mill further includes a two part housing which may be readily opened in order to permit cleaning and servicing of the internal components of the mill.

This is a continuation of my application Ser. No. 100,472, filed Sept.24, 1987, now abandoned.

DESCRIPTION OF THE INVENTION

The present invention relates generally to a meat emulsifying andprocessing system of the type in which ground or chopped meat isdelivered to an emulsifying mill, is broken into a fine emulsion, andthen is delivered from the mill to a stuffer or the like. Such systemsare conventionally used in the processing of sausage, bologna,frankfurters, poultry, fish and similar products in order to reduce themeat content such meat products into a cohesive emulsion which may bestuffed into an outer casing.

Most commercially available meat emulsifying mills employ a high speedrotary cutter which force meat and fat products, and added water,through a perforated plate for breaking the product into relatively fineparticles, blending the product into a homogeneous mixture, and raisingthe temperature of the product sufficient that the protein from the meatcells is released and partially denatured thereby acting to bond theproduct together so as to enable the product to retain fat and moistureupon cooking. Under the optimum temperature conditions this partiallydenatured protein forms a stringy, coagulum matrix trapping the meatparticles and resulting in the optimum retention of fat, water and meatparticles in the emulsion product. For economy of production, it isdesirable that the final product contain as much fat and added water aspossible while still meeting government specifications. It also isdesirable to use the least cost formulation blending for the fat andlean meats.

Emulsion stability is the ability of the finished product to retain fatand added water to a maximum degree upon cooking. If during theemulsification process the temperature of the product is not increasedsufficiently to effect the release and partial denaturation of theprotein from the meat product, then upon cooking, the fat and moisturewill be released from the product, reducing the size of the cookedproduct and creating an unsightly accumulation of grease and fat aboutthe outside thereof. On the other hand, if during emulsification, thetemperature increase is excessive, then the binding cohesive effect ofthe protein matrix tends to become destroyed, such that upon cooking ofthe product, fats and moisture are again released. It has been foundthat as the temperature change effected during emulsification approachesthe preferred emulsification temperature for a particular product,increased fat and moisture retention is possible in the final product.As the temperature increases beyond the preferred temperature for suchproduct, fat and moisture retention in the final product is reduced.

In an effort to achieve the desired temperature increase duringemulsification, it has been the practice to utilize standardizedperforated plates, the aperture size in the plate being selected to mostclosely result in the desired temperature increase. The smaller theaperture size in the perforated plate, the greater working of theproduct that is necessary in breaking the product down sufficiently sothat it may be forced through the perforated plate, and thus, thegreater the temperature increase. Precise temperature control, however,has not been possible. For example, if a standardized perforated platehaving 1.7 millimeter diameter apertures is utilized, the temperatureincrease for a particular product may be only 80% of the preferredamount. If the next smaller standardized perforated cutting plate isused, i.e., one with 1.4 millimeter apertures, due to the greaterworking of the product necessary to achieve passage through such smalleropenings, the temperature may rise to 120% of the optimum. In neitherinstance, therefore, would maximum emulsion stability be achieved.

Moreover, although it is preferable to emulsify the meat into as fine ofparticles as possible, for the reasons indicated above, the aperturesize in the perforated plate heretofore has been limited by temperatureconsiderations. In practice, perforated plates with apertures of 1.4millimeters has been about the smallest size that has been permissible.Even then, it is necessary to extensively prechop many meat by productsin bowl cutters and to process it through double stage meat grindersprior to reaching the emulsification mill. Such pregrinding of theproduct requires relatively expensive equipment and additional energyrequirements, and as a result, increases the cost of the processing.When relatively tough inexpensive by-products are used, greaterpreworking of the product is required, and effective emulsification iseven more difficult within temperature limitations. Heretofore, it hasgenerally not been possible to emulsify meat products which have beenpreground only through a single stage meat grinder.

The degree of emulsification further can be a function of the rpm of thecutter in the emulsification mill and the number of cutting blades orknives on the cutter. The cutting blades typically are designed to forcethe product through the perforated plate of the emulsification mill.While increasing the number of blades on the cutter will enhance thethoroughness and fineness of the cut for a given rpm of the cutter,heretofore, horsepower and temperature limitations have limited thenumber of blades on the cutter to no more than three.

Furthermore, since the cutting blades in the emulsifier commonly aredesigned to force the product through the perforated plate, this createsa negative pressure at the inlet side of the mill which tends tointroduce air into the product as it is drawn from the feed hopper tothe mill. Air in the processed product will allow bacterial growth morerapidly, and thus, reduce the shelf life.

It is an object of the invention to provide an emulsification systemthat is adapted for more thorough and efficient emulsification of meatby-products.

Another object is to provide an emulsification system as characterizedabove that is operable to more reliably process emulsified meat productswith optimum emulsion stability.

A further object is to provide an emulsification system of the foregoingtype which permits more economical emulsification and blending of lessorexpensive and tougher meat by-products, while retaining product quality.

Yet another object is to provide an emulsification system of the abovekind that permits relatively precise control of the temperature changeduring emulsification, and thus, better control in the emulsionstability of the processed product.

Still a further object is to provide an emulsification system of suchtype which permits utilization of a perforated cutting plate in theemulsifier with smaller sized apertures than heretofore possible so asto enable the meat products to be broken down into a finer and morecohesive emulsion. A related object is to provide such an emulsificationsystem which permits efficient emulsification of even relatively toughmeat byproducts that have been preground only by passage through asingle stage meat grinder.

A further object is to provide an emulsification system which permitsthe use of a cutter having a greater number of cutting blades thanheretofore possible.

Yet another object is to provide an emulsification system which is lesssusceptible to the introduction of air into the emulsified product andwhich is operable for more reliably processing emulsified products withgood shelf life.

A further object is to provide an emulsification system which lendsitself to substantially automated control.

Other objects and advantages of the invention will become apparent uponreading the following detailed description and upon reference to thedrawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of a meat processing system having anemulsifier embodying the present invention;

FIG. 2 is an enlarged side elevational view of the emulsifier shown inthe illustrated system, taken in the line of 2--2 in FIG. 1, certainparts being broken away and shown in section;

FIG. 3 is a side elevational view of the illustrated emulsifier, takenin the plane of line 3--3 of FIG. 2;

FIG. 4 is an enlarged fragmentary section taken in the plane of line4--4 in FIG. 3;

FIG. 5 is a chart depicting the temperature pressure versus emulsionstability for a typical emulsified product;

FIG. 6 is an enlarged section taken in the plane of line 6--6 in FIG. 4and showing the rotary cutter of the emulsifier;

FIG. 7 is an elevational view of the cutter shown in FIG. 6;

FIG. 8 is a fragmentary section taken in the plane of line 8--8 in FIG.6;

FIG. 9 is an enlarged section of an alternative form of rotary cutteradapted for use in the illustrated emulsifier;

FIG. 10 is an elevational view of the cutter shown in FIG. 9;

FIG. 11 is a fragmentary section taken in the plane of line 11--11 inFIG. 10; and

FIG. 12 is a schematic diagram of the controls for the illustrated meatprocess system shown in FIG. 1.

While the invention is susceptible of various modifications andalternative constructions, a certain illustrated embodiment thereof hasbeen shown in the drawings and will be described below in detail. Itshould be understood, however, that there is no intention to limit theinvention to the specific form disclosed, but on the contrary, theintention is to cover all modifications, alternative constructions andequivalents falling within the spirit and scope of the invention.

Referring now more particularly to FIG. 1 of the drawings, there isshown an illustrative meat processing system 10 adapted for emulsifyingvarious meat products, such as beef, pork, poultry and mixtures thereof,and for stuffing the emulsified product into casings in order to formprocessed products such as sausage, bologna or frankfurters. The meatprocessing system 10 includes a mixer 10 into which lean meat, fat,water and condiments are subjected to final mixing and blending prior toemulsification. Final correction of the moisture and fat content of theproduct may be effected in the mixer 10, as is known in the art. Theproduct entering the mixer 10 is preground or prechopped and a typicalproduct may contain sixty percent (60%) lean meat, thirty percent (30%)fat and ten percent (10%) moisture. As will become apparent, in thesystem of the present invention, lesser preworking of the product isrequired than in conventional emulsification mills, such preworkinggenerally being effected only by passage of the product through a singlestage meat grinder.

Product from the mixer 10 in the illustrated system is discharged into atransfer hopper 11 and then is pumped upwardly through a chute 12 andinto a large supply silo 13 by a positive displacement transfer pump 14at the lower end of the transfer hopper 11. The product then isdelivered to an emulsifying mill 15 which is in the nature of a highspeed grinder adapted to break the product down into a very finecohesive emulsion. Emulsified product from the mill 15 is deliveredthrough a discharge chute 16 to a receiver 17, which in this instance,is a stuffer 17 adapted to inject the material into appropriate casingsat high speeds. A typical processing system may be capable of handlingabout 15,000 pounds of product per hour.

The components of the illustrated emulsification mill 11 are supportedon a wheeled cart 18, as best shown in FIGS. 2 and 4. In general, themill 11 includes a tubular housing 20 (FIG. 4) defining a chamber whichcontains a rotary cutter 21; a conventional ratchet tooth gristle ring22 that is stationary; a perforated extrusion or cutting plate 23 whichalso is stationary; a stationary backing support plate 24 for thecutting plate; and a three-bladed rotary discharge impeller 15 whichslings the emulsified product out of an outlet o discharge port 26 inthe housing 20 and into the chute 16 for delivery to the stuffer 17. Thecutter 21 and the discharge impeller 25 are adapted to be rotated by atubular shaft 28 having a splined end portion 28A which is telescopedslidably with the cutter. A large sleeve 30 is bolted to one end of thehousing 20 at 31 and to the cart 18 at 32 and houses a pair of bearings33 which rotatably support the shaft 28. For driving the shaft 28, anelectric motor 35 (FIG. 2) supported within an enclosure 36 on the cart18 has a drive pulley 37 operably connected to a driven pulley 38 on theshaft 28 by a plurality of belts 40.

As the cutter 21 is rotated, it co-acts with the forward side of thecutting plate 23 to grind the product finely and to extrude the productthrough small perforations or apertures 42 (FIG. 8) in the plate. Toenable the contact pressure between the cutter and the perforated plateto be adjusted, an elongated draw bar 43 (FIG. 4) extends through thecenter of the shaft 28 and its forward end portion 44 interlocks with aretaining collar 45 on the cutter. A nut 46 is threaded onto the rearend of the draw 43 and compresses a coil spring 47 against the rear endof the shaft 28. Thus, the spring urges the draw bar from left to rightin FIG. 4 and biases the cutter 27 against the perforated plate 23. Byadjusting the nut 46 to the left or to the right on the draw bar 43, theforce exerted by the spring 47 may be increased or decreased,respectively, to adjust the pressure of the cutter against the plate.Adjustment of the nut may be effected by a removable hand wheel 48having a key 49 adapted to interlock with a keyway 50 in the nut. Forlimiting the biasing force of the spring 47 to a predetermined maximumamount, a sleeve 51 is mounted on the shaft and has an outwardlyextending annular flange 51A at one end thereof, against which one endof the spring 47 engages (FIG. 4). The opposite end of the sleeve 51serves to limit threaded movement of the nut 46 onto the shaft 28, andthus limit axial compression of the spring.

As is known in the art, during the emulsification protein is fracturedfrom the meat cells as the product is broken up by the rotating cutter21 and is forced through the perforations 42 in the plate 23 with aresulting temperature increase. The fractured protein is a glue-likesubstance that acts to retain fat and moisture in the mixture and tobind the fat, the moisture and the lean meat together as a cohesivemass. As the product is broken up in the mill 15, it inherentlyexperiences an increase in temperature, such as in the range of 15 to 25degrees F, due to the action of the cutter 21 and the forcing of theproduct through the apertures 42.

In accordance with the invention, the emulsifier is adapted to morereliably emulsify the meat product to an optimum temperature rise forachieving maximum emulsion stability in the processed product. Moreparticularly, the system of the present invention is adapted to permitrelatively precise control over the discharge temperature of theemulsification mill by force feeding the product to the mill underpositive pressure and by selectively increasing or decreasing the flowif the discharge temperature rises or falls, respectively, beyondcertain target values. To this end, in the illustrated embodiment, forcefeeding is effected by a positive displacement pump 52 (FIG. 1), such asa gear pump located at the bottom of the supply silo 13 and driven by anelectric motor 53 having a variable speed control The discharge side ofthe pump 52 is connected by a flexible conduit 55 to an inlet pipe 56(FIGS. 2 and 4) attached to the forward end of the housing 20 andcommunicating with the chamber defined by the housing.

In contrast to conventional emulsification mills which rely on a gravityfeed to the emulsifier, and in which a significant negative pressure iscreated by the rotating cutter on the upstream side of the perforatedplate, the pump 52 in the illustrated system draws product from the silo13 and positively feeds the product to the mill by way of the conduit 15and inlet pipe 56. The positive force feed is at a controllable flowrate, as determined by the speed of the pump 52, which in turn permitscontrol of the temperature rise during emulsification. For example, ifthe temperature of the product discharging from the emulsifier risesabove the predetermined target value for achieving optimumemulsification stability for a particular product, the speed of the pumpcan be increased in order to force more product through the mill in agiven period of time, and thereby, shorten the time the product is inthe mill. This produces a smaller temperature rise in the productpassing through the mill and enables the discharge temperature to belowered. On the other hand, if the discharge temperature is below thepreferred or critical value, the speed of the pump 52 may be reduced toenable the product to remain in the mill for a longer period of time,and thereby, be more thoroughly emulsified through optimum proteinrelease and partial denaturation.

The relation of the temperature rise during emulsification to theemulsion stability in the final product is illustrated by reference tothe chart shown in FIG. 5. At the outset, for a particular product, thedesired temperature rise for achieving optimum emulsion stability can beclosely estimated or determined. From FIG. 5, it can be seen that thetemperature increase during emulsification is a function of the feedinlet pressure. In the illustrated example, the optimum emulsionstability is achieved by a 20° F. temperature increase during emulsion,which can be effected by maintaining an inlet feed pressure of about 25psi. In the event the temperature increases above 20° F., which can bedetermined through a temperature sensor 98 at the outlet of the emulsionmill, the speed of the pump 52 may be increased so as to increase theinlet feed pressure and the through put of the emulsification mill. Inthe event the temperature rise falls below the predetermined 20° F., thepump 52 may be slowed, thus lowering the inlet feed pressure and millthrough put, so as to again achieve the desired temperature increase andoptimum emulsion stability in the processed product.

It will be understood by one skilled in the art that the speed of thepump 52 may be adjusted in various ways as, for example, by changing thesetting of the variable speed control 54 of the motor 53. The motor mayhave an electronic speed control, such as the control 54, oralternatively, the pump and the motor may be connected by a pulley andbelt drive having variable diameter pulleys which may be adjusted tochange the speed of the pump relative to the speed of the motor.

In keeping with the invention, the emulsifier of the present inventionis adapted to utilize a cutting plate 23 with smaller diameterperforations 42 than heretofore possible, and thus, achieve finercutting during emulsification and a more cohesive emulsion. By forcefeeding the product into the mill by the pump 52, it has been foundpossible to utilize apertures 42 in the cutting plate as small as 1.0millimeter. Conventional emulsifiers, in contrast, have been unable toeffectively operate with perforated plates having apertures smaller thanabout 1.4 millimeters, which have nearly twice the cross sectional area.While not fully understood, it is believed that because of the positivepressure at the inlet of the emulsifying mill generated by the pump 52the product tends to be physically forced through the relatively smallapertures, resulting in finer emulsification than previously possiblewhile still operating within acceptable temperature limitations.

Moreover, because a positive pressure is maintained at the inlet of themill, there is less tendency for air to be drawn into the emulsifiedproduct, as compared to conventional emulsification mills. Hence, thereis less likelihood of premature promotion of bacterial growth in theprocessed product and shortening of shelf life. In addition, theemulsifier of the present invention has been found to enable effectiveemulsification of many relatively tough, inexpensive meat by-products,which heretofore have been difficult and more costly to emulsify.Emulsification of such by-products can be achieved in the present systemwith minimal preworking, typically only requiring passage of the productthrough a single stage meat grinder, again in contrast to conventionalemulsification systems which require extensive bowl cutting andmulti-stage pregrinding.

It has been found that the emulsification system of the presentinvention can be operated with significant cost savings overconventional systems, utilizing least cost blending fat and lean meatproducts and operating with more efficient power consumption. Onespecific installation constructed in accordance with the invention, forexample, employed a 100 horsepower motor 35 for driving the mill 15 anda 10 horsepower motor 53 for driving the pump 52, and was found tooperate with the same capacity as a gravity feed system having a 125horsepower motor for driving the mill and a 200 horsepower motor foroperating a bowl chopper to prework the product prior to emulsification,resulting in a total horsepower requirement of 325 horsepower.

In carrying out the invention, the cutter 21 in this instance isconfigured so as to enhance emulsification of stiff and cold product, byassisting in forcing the product through the perforated cutting plate23. The illustrated cutter 21, as shown in FIGS. 6-8, includes a centralbody or hub 78 which receives the splined end portion 28A of the shaft28 and is adapted to be rotated in a clockwise direction, as viewed inFIG. 5. Three blade holding wings 79 are spaced angularly around and arewelded rigidly to the hub. Each wing is inclined such that itsdownstream face is at an acute angle A of about 15 degrees relative tothe upstream face of the perforated cutting plate 23. Welded at 80 (FIG.8) to the downstream face of the trailing edge portion 79A of each wing79 is a blade holder 81 formed with a slot 82 which receives a cuttingblade 83. Each cutting blade is secured in its slot by a set screw 84located in a tapped hole in the blade holder 81 which acts to clamp theblade in the slot.

As shown in FIG. 8, each blade holder 81 is formed with an inclineddownstream face 85 that is located at an acute angle B of about 45degrees relative to the upstream face of the perforated plate 23. Eachwing 79 includes a leading edge portion 79B that extends well beyond theface 85 and is inclined at the angle A. When the cutter 21 is rotatedclockwise, the inclined leading edge portions 79B of the wings 79 make arelatively wide initial cut through the product and force the productagainst the differently angled faces 85 which then push the productagainst the plate 23 for shearing by the blade 83. Being extended beyondthe inclined faces 85 of the blade holders 81 and being inclined at asubstantially smaller angle than the faces 85, the leading edge portions79B of the wings 79 produce a relatively wide cut, enabling acomparatively large quantity of product to be forced through the plate23 in a given period of time so as to increase the through put capacityof the mill 18. Since the product is being force feed to the cutter bythe pump 52, there is no opportunity for air to be drawn into theemulsified product, as in the case of conventional emulsifiers whichcreate significant negative pressures upstream of the cutter blade.

Referring now to FIGS. 9-11, there is shown an alternative embodiment ofcutter for use in the emulsification mill, wherein pans similar to thosedescribed above have been given similar reference numerals with adistinguish prime added. The cutter 21' in this instance has a greaternumber of blade carrying arms, as compared to cutters used inconventional emulsifiers, so as to significantly increase cutting actionduring emulsification. The illustrated cutter 21' has a hub 78' withfour blade carrying arms 81' extending outwardly therefrom in tangentialrelation to the hub 78', although it will be appreciated that even agreater number of arms could be utilized. The arms 81' in this instanceeach have a substantially rectangular cross section, as illustrated inFIG. 11, with a forward face 86 disposed in substantially parallelrelation to the upstream face of the cutting plate 23', such that uponrotation of the cutter 21' the arms exert no significant forwardpressure, or pumping action, against the product in the mill. Each arm81' carries a cutting blade 83' that is received within a slot 82' withthe cutting blade extending outwardly thereof in angled relation to theforward face of the arm. An appropriate set screw 84' mounted in atapped hole in the arm secures the cutting blade in place.

It will be appreciated that for a given rpm, the cutter 21' will effect25% more cuts per revolution than a conventional three bladed cutteroperated at the same speed. Moreover, since the cutter 21' does not haveto force feed the product through the cutting plate 23' power to thecutter it is not consumed for the purpose. As a result, it has beenfound that a four bladed cutter 21' may be operated at substantially thesame rpm as conventional three bladed cutters, to achieve significantlygreater cutting action, with no greater horse power requirements. Sincethrough put of the product is effected primarily by the pump, it stillis possible to maintain relatively precise control of the temperaturerise during emulsification, and thus emulsion stability, even when usinga cutter plate with perforations of 1.0 millimeter in diameter and less.

In accordance with a further more detailed aspect of the invention, thehousing 20 of the mill 15 is formed by two separate tubular sections 60and 61 (FIGS. 2 and 4) which may be easily disassembled to enable theoperating components of the mill to be cleaned, repaired or replaced.The housing section 60 in this instance is a downstream section securedby the screws 31 to the sleeve 30. The downstream housing section 60surrounds the perforated plate 23, the backing plate 24, and thedischarge impeller 25. The housing section 61 is an upstream sectionthat surrounds the cutter 21 and the gristle ring 22 and supports theinlet pipe 56.

The upstream forward housing section 61 normally is telescoped over thedownstream housing section 60 and is sealed thereto by an O-ring 63, asshown in FIG. 4. The two housing sections normally are locked togetherby a pair of bolts 64 and 65 (FIG. 3) and a pair of nuts 66 and 67. Thebolt 64 extends through a flange 68 (FIGS. 2 and 3) on the downstreamhousing section 60 and an ear 69 (FIG. 3) on the upstream housingsection while the bolt 65 extends through the flange 68 and adiametrically spaced hook-like ear 70 on the upstream housing section.When tightened, the nuts 66 and 67, respectively, clamp the ears 69 and70 to the flange 68 and thereby lock the two housing sections intelescoping relation as shown in FIG. 4.

When it is necessary to service the mill 15, the supply conduit 55 isreleased from the inlet pipe 56 by loosening a clamp 71 (FIGS. 2 and 3)which normally secures the conduit to the pipe. Thereafter, the nuts 66and 67 are loosened on the bolts 64 and 65 to enable the upstreamhousing section 61 to be pulled out of telescoping relation with thedownstream housing section 60 by means of a ball-type handle 72 on theupstream housing section. The handle then may be used to swing theupstream housing section 61 about the bolt 64 and to an open positionrelative to the downstream housing section 60 as shown in phantom linesin FIG. 3, the hook-like ear 70 releasing the bolt 65 to permit suchswinging. With the upstream housing section 61 in its open position,there is free access to all of the components in both housing sectionsso as to enable convenient cleaning and servicing of such components.

As shown in FIGS. 2 and 3, a sensing rod 74 is biased against the ear 69by a coil spring 75. When the two housing sections 60 and 61 are infully assembled relation, the push rod 74 is depressed rearwardly by theear 69 and closes a safety switch 76 (FIG. 2) which is in the energizingcircuit of the motor 35 of the mill 15. When the upstream housingsection 61 is pulled away from the downstream housing section 60, theear permits the sensing rod 74 to move to a position opening the switch76 so as to disable the motor 35 and prevent the mill from beingoperated when the housing section 61 is in a position other than itsfully closed position.

In accordance with still a further aspect of the invention, theillustrated emulsification system is adapted for relatively precisecontrol, for more reliably producing a quality emulsified product withoptimum emulsion stability. The control for the illustrated system isschematically shown in FIG. 12. Briefly, the system includes a controlpanel 90 with two 24 hour strip chart recorders 91 and 92. The recorder91 includes a marker 93 which plots the temperature of the product inthe mixer 10 as a function of time, such temperature being detected andsignaled by a thermalcouple probe 94. The recorder 92 includes threemarkers 95, 96 and 97 which respectively plot, in different colors, thetemperature of the product at the inlet 56 of the mill 15; thetemperature of the product at the outlet 26 of the mill; and thepressure existing at the inlet of the mill. The inlet and outlettemperatures are detected and signaled by thermalcouples 98a and 98,respectively, while the inlet pressure is signaled by a pressuretransducer probe 99. Digital read-outs 100 and 101 on the control panel90 display the inlet and outlet temperatures, respectively, and may beused in setting the speed of the pump 52 to maintain an appropriatetemperature differential in the product as the product is processedthrough the mill. An indicating light 103 on the control panel isenergized when the transducer 99 signals that there is positive workingpressure at the inlet of the mill.

The control panel 90 further comprises a "cycle on" switch 104, a "cycleon" indicating light 105, a "power on" light 106, a "cycle off" switch107 and an emergency stop button 108. Additional lights 109 and 110 onthe control panel 90 respond to conductivity transducers 111 and 112,respectively, which detect and signal when the level of product in thestuffer 17 is high or low. The level of the product in the supply silo13 is detected by similar high and low level sensors 113 and 114 whichenergize warning lights 115 and 116, respectively, if there is eithertoo much or too little product in the silo. The level of the product inthe transfer hopper 11 also may be detected by high and low load leversensors 120 and 121 which energize appropriate warning lights 122, 123.

The control panel 90 in this instance is completed by a pair oftwo-position selector switches 117 and 118. When the switch 117 is inthe one position, both the mill motor 35 and the pump motor 53 areconditioned for operation so as to permit the system to function in anormal manner. In the other position of the switch 117, the mill motor35 is disabled but the pump motor 53 is permitted to operate in order toprime the mill 17 preparatory to start-up of the overall system.

The switch 118 has a "manual mode" position and an "automatic mode"position. When the switch 118 is in its "manual" position, the system isstarted and stopped by actuating the "cycle on" switch 104 and the"cycle off" switch 107, respectively. If the switch 118 is in its"automatic" position, the mill is initially started by actuating the"cycle on" switch 104 but then is shut down automatically by the highlevel sensor 111 of the stuffer 17 and is restarted automatically by thelow level sensor 112 of the stuffer.

Appropriate controls preferably are provided for preventing operation ofthe rotary cutter until a predetermined positive pressure is sensed bythe pressure sensor 99 on the inlet side of the cutter. During operationof the mill, as previously described, the emulsification temperatureincrease can be controlled to the desired amount by controlling thespeed of the variable speed positive displacement pump. It will beunderstood that this may be manually accomplished, or alternatively, anappropriate automated control can be provided which controls the speedof the pump as a function of the emulsion temperature differentialbetween inlet and outlet.

From the foregoing, therefore, it can be seen that the emulsificationsystem of the present invention can be operated to more thoroughly andefficiently emulsify meat by products with optimum emulsion stability.The system permits the use of smaller diameter perforations in thecutting plate and greater numbers of blade carrying arms on the rotarycutter for effecting finer and more thorough emulsification, while stillpermitting relatively precise temperature control.

I claim as my invention:
 1. A meat emulsifying and processing system includinga variable speed positive displacement pump having an inlet adapted to receive a supply of pre-cut meat and an outlet to deliver said pre-cut meat under pressure; speed control means associated with said pump for selectively increasing and reducing the speed of said pump during operation based upon a temperature differential of the meat being emulsified to thereby vary the rate of flow of meat from said pump; an emulsifying mill for breaking said pre-cut meat into a fine emulsion, said mill including a housing, an inlet adapted to receive said pre-cut meat from said pump, an outlet downstream from said inlet, .[.a perforated plate connected to said housing between said inlet and outlet,.]. a rotary .[.cutter, adjacent and upstream of said perforated plate, said cutter adapted to force said pre-cut meat through said perforated plate,.]. .Iadd.cutter located between said inlet and said outlet, .Iaddend. a rotary impeller disposed within said housing downstream of said .[.perforated plate.]. .Iadd.rotary cutter .Iaddend.adapted to convey emulsified product out of said outlet, and drive means for rotating said cutter; first temperature sensing means associated with said inlet of said emulsifier to detect the temperature of said meat at said inlet; first display means for displaying the temperature of said meat at said inlet; second temperature sensing means associated with said outlet of said emulsifier to detect the temperature of said emulsion at said outlet; second display means for displaying the temperature of said emulsion at said outlet, said temperature sensing means and said display means operative to enable a processing system operator to compare the temperature differential between said first and second temperature sensing means and, when said temperature differential deviates from a predetermined value, to activate said speed control means to vary the speed of said pump to thereby control the temperature rise of said meat during emulsification.
 2. A meat emulsifying and processing system as in claim 1 including automated control means associated with said first and second temperature sensing means and said speed control means operable when said temperature differential deviates from a predetermined value to signal said speed control means to vary the speed of said pump to thereby control the temperature rise of said meat during emulsification.
 3. A meat emulsifying and processing system as in claim 2 in which said automated control means is operative to signal the speed control means to increase the speed of said pump when said temperature differential exceeds a predetermined value and to decrease the speed of the pump when said temperature differential falls below a predetermined value.
 4. A meat emulsifying and processing system as in claim 1 including pressure sensing means positioned adjacent said inlet of said emulsifying mill adapted to sense the inlet pressure of said mill, said pressure sensing means connected to said drive means such that said drive means is activated only after a pressure above a predetermined value is sensed at said inlet of said emulsifying mill.
 5. A meat emulsifying and processing system as in claim 4, in which said drive means is deactivated when said inlet pressure of said emulsifying mill drops below a predetermined value. .Iadd.
 6. A meat emulsifying and processing system as in claim 1 including a perforated plate connected to said housing and adjacent to and downstream of said rotary cutter, said rotary cutter adapted to force said pre-cut means through said perforated plate. .Iaddend. 